Smart motorways

This was clearly a very topical subject locally – our meeting on 28 June had been advertised in the Congleton Chronicle, and we had 62 people there, of whom 22 were visitors, and so we had to do a quick shuffle to move out of the small side room at Astbury Village Hall into the main hall.

John Philips, the Project Manager, and Arun Sahni, both civil engineers for Highways England who are working on the project to convert the stretch of the M6 from junction 16 to junction 19 into a ‘smart motorway’, came to talk to us about the work involved.
Arun started off by explaining with the help of pictures and graphics some of the civil engineering and technology that goes into such a huge project. The work on the J16-J19 length of the M6 was originally scheduled to take two years, but unforeseen problems such as the discovery of a huge wall of concrete buried underground alongside the carriageways near J19 had added considerably to the timescale – this concrete all had to be dug up because the new surfacing would be made of flexible material, so could not be laid on a solid base. The old concrete had all been recycled, so that some of it would be used in the current construction and some used elsewhere. Highways England was able to report that 98% of the waste from the site had been recycled and re-used on the same project.

Incidentally, Arun informed us that when this new technology was originally proposed, the term used was ‘Managed Motorways’, but the Transport Minister at the time used the term ‘Smart Motorways’ and unfortunately this inaccurate description – the motorway itself doesn’t do anything – stuck.

Highways England manages 1,700 miles of motorway and 2,700 miles of trunk roads in the UK, which still only comprises 2.4% of the entire road network. Traffic density is forecast to increase by 44% by the year 2035, which is why they have to try to increase road capacity wherever possible. Converting the hard shoulder means the road can carry more vehicles without impacting on the environment, as no additional land is needed.

Several years ago, the M42 around the outskirts of Birmingham became the pilot motorway during peak hours for what was then called Dynamic Hard Shoulder Running. Traffic officers used cameras to check that the shoulder was clear before opening it to traffic, and if there was any obstruction at all they put a red cross on the gantry for that lane, with arrows to move traffic across into the live lanes. Gantries were constructed at intervals of 500m or less to facilitate early warnings of problems. It was found that journey times improved by up to 24%, and the personal injury accident rate dropped by 55.7%. Noise and pollution levels also went down, as traffic was no longer crawling or stop-starting in the worst areas. It was noticed, however, that only 12% of the vehicles that could use the hard shoulder were actually using it, presumably because people didn’t understand how it worked.

The new term for the stretch through our area is ‘all-lane running’, where what used to be the hard shoulder is in use all of the time provided there are no obstructions, and there are refuges built in at approximately one- to one-and-a-quarter-mile intervals for vehicles to pull into if they or their passengers have problems. The matrix signs will usually overhang lane 1 where there are no gantries. They will show open lanes in yellow, closed ones in red, arrows to direct traffic into adjoining lanes, advisory or compulsory speed limits, and have two lines at the bottom of the sign for a limited amount of written information (restricted to 12 characters per line).

Highways England have commissioned about 100 miles of ‘smart motorway’ so far, and have installed cameras that provide 140% coverage of the carriageway area – the reason for the over-capacity is that if a camera breaks down there should always be other cameras to cover the same area. The cameras also have infra-red lenses so that the operators can see equally well at night in rural areas like Cheshire, where there is no road lighting. Highways England operate their own cctv coverage of the stretch at their Sandbach HQ because the existing camera network has had to be taken out of commission.

John then took over to talk about the work being carried out on existing structures such as over- and under-bridges, many of which are at least 50 years old now and suffering decay caused by road salt. The opportunity was being taken to survey all such structures, carry out repairs, and add protection for the future. All of the existing drainage system was equally old and time-expired, so it had to be replaced and extended to cope with the extra width of the carriageways. The new lanes had to be moved across as much as possible so that the new infrastructure could be fitted into the left side of the existing hard shoulder. The new lanes 1 and 2 would be the same width as the present ones, but the new lane 3 would be narrower than the existing one, and lane 4 would be narrower still, as lorries and coaches would not be allowed into that lane in normal circumstances.
In order to fit the four lanes in where there were only three plus a narrower hard shoulder previously, some space also had to be stolen from the central reservation, which meant that both the shoulder and the central reserve had to be strengthened to withstand having traffic running on them constantly. The old steel central barrier was being replaced by a concrete one, which was either created on site by a machine or could be brought in ready for installation. The method used depended to a certain extent on the road layout – bends were easier to cope with using the machine that made the barrier as it went along.

The work on the J16-J19 stretch commenced (rather appropriately) in March 2016, and was now due to finish in March 2019. This 30km length of carriageway carried some 120,000 vehicles a day, and current statistics showed that 60% of cars that broke down in the roadworks area were moved within 30 minutes. Sixty-five HGVs had broken down or stopped in the same section during the work period to date, often due to their digital tachograph systems running out.

The next section of the M6 in this area to be converted will be from J15 to J13, but that work will not commence until the current stretch is finished and working.